reverse polarity glow

B

Blitz

.
Jul 10, 2007
676
Seidelmann 34 Atlantic Highlands, NJ
Roger's recent post got me thinking. I've once seen a situation in which all the polarity checked out with one of those $3 testers (maybe $6 now) on the dock and boat when the AC cord was hooked up to shore power. The boat had two reverse polarity indicators hooked up at a breaker within two feet of the shore power connection and another older unit off the original breaker greater than ten foot from the shore power inlet. The newer blue seas polarity lights on the boat first breaker near the inlet had the usual red for reverse polarity and green anytime the power was on.

The issue occurred when the boat's battery charger was on, the ac vacuum was running or a ceramic heater was running in which only the boat's blue seas red reverse polarity light would glow slightly.

What was going on here?
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
22,770
Catalina 34 224 Maple Bay, BC, Canada
The rp lights work with micro-volt neon lamps and some resistor (?), at least the older ones did. Once a large AC load was on they did weird things. The newer ones? maybe not. Do some research on the basics and you'll figure it out. I did it by observation.
 
Bill Roosa

Bill Roosa

.
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
high amp loads can slightly load the ground wire due to resistance in the various neutral connections over the resistance in the ground wire connections. The slightly elevated voltage on the ground causes the lamp to glow.
Since the place where neutral and ground come together is at the shore meter you can expect the lamp glow to change with the marina, the shore power cable you use and over time as the boat connections age and corrode.
This is not something "of great concern" but you would want to keep an eye on it to see if it is getting worse over time.
 
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